Electrochemical cells form the basis of a variety of analytical sensors. Electrochemical cells generally have two or more electrodes of the cell and are coupled to an analyzer that measures an electrical characteristic of the cell in order to infer a property of a sample within, or otherwise coupled to, the cell. Many electrochemical cells include a measurement electrode and a reference electrode. The reference electrode will generally include a chamber that houses a reference electrode fill solution. A junction, of some sort, allows electrochemical interaction between a sample solution and the fill solution. Electrochemical cells can be used for oxidation/reduction potential (ORP) sensors, pH sensors, or other suitable sensors.
One type of junction used with reference electrodes of electrochemical cells is known as a liquid junction. A liquid junction uses a relatively small passageway that is in fluidic communication with both the sample solution and the reference fill solution. In order to achieve a stable potential at the liquid junction, it is generally preferred that at least some flow of reference fill solution through the passageway into the sample solution be induced. With a “flowing” liquid junction, the reference electrode fill solution constantly flows through the liquid junction into the sample solution.
As demands for pH measurement of high purity water increase, new sources of error that were previously unknown or misunderstood must be addressed. Providing a pH sensing system for high purity water applications that is able to provide increased accuracy and/or precision would benefit the art of process analytic sensing.